Contact element for plug-in sockets



Oct. 18, 1949. 5.. T.- DEAKIN CONTACT ELEMENT FO PLUG-INSOCKETS Filed Aug. 2, 1946 F645 if I v 16 f v 15 STbn/fiy T Dea kin Veni'or j i wbw Patented Oct. 18, 1949 CONTACT ELEMENT FOR PLUG-IN SOCKETS Stanley Thomas Deakin, Ewell West, England, assignor to British Mechanical Productions Limited, London, England, a British company Application August 2, 1946, Serial No. 688,033 In Great Britain April 4, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires April 4, 1965 3 Claims. 1

This invention relates to metal socket members for electrical pin-plug and socket connectors. The invention is particularly (but not exclusively) concerned with socket members for thermionic valve holders of the type comprising an insulating plate formed with a number of apertures (usually arranged as an annular series) within which a corresponding number of metal socket members are secured, the arrangement being such that access openings to the socket are presented at one face of the plate while the main portions of the socket extend from the opposite face and each provides in addition a tag or equivalent terminal to take a circuit wiring connection.

According to the present invention a socket member, for an electrical pin-plug and socket connector, is fabricated from a sheet metal blank which is bent to the shape of a tube and which is preformed with oblique slots or slits open at one end and arranged to provide, in the finished socket member, two or more resilient and obliquely extending contact elements.

In one construction according to the invention, the blank is formed to provide three elements, namely two resilient obliquely disposed contact elements separated at one side by a third element constituting a tag or equivalent terminal. Preferably the blank is so formed that the finished socket member tapers in its length, the narrow end being remote from the access opening to the socket. Preferably also the arrangement is such that the necessary resilient contact pressure (i. e. on the co-operating plug-pin) is provided solely by the obliquely disposed elements, 1. e. without relying on the tag element for any part, or any appreciable part, of this function.

An example embodying the foregoing and other features of the invention will now be described with reference to the accompanying drawings, in which:

Figure l is a plan view of the blank from which the socket member is made;

Figures 2 and 3 are elevations at right-angles of the finished socket member; and

Figure 4. is an end view of the socket member looking in the direction of the arrow in Figure 2.

Like reference numerals indicate like parts in the several figures.

In this example, the blank comprises a main portion l9 and a central strip-like extension II. The main portion I0 is formed with oblique slits 12 open at one end and the side edges I3 of the portion 1 ll opposite the slits l2 are inclined at the same angle as the slits. outer end of the extension I l provides a terminal tag apertured at I4 to form an eye.

In order to form the socket member the blank is bent to tubular shape and the wing pieces l5- constituted by the parts of the main portion Ill between its marginal edges l3 and the slits H- are pressed towards one another-and towards the extension H, thus forming a tapered tube with the narrow end adjacent to the extension. An annular bulge I6 is upset at the broad end of the tube to provide a flange for the attachment of the socket member to an insulating plate, shown in chain lines at I! in Figure 3. The portion of the socket member beyond the bulge IE on the side remote from the tag is of cylindrical form, adapted to be inserted in a circular aperture in the plate I l, the outer end of this cylindrical portion being riveted over in order securely to anchor the socket member to the plate. A bend I8 is formed intermediate in the length of the extension I I, and at a region of reduced width, so that the eye end may readily be bent over to facilitate the attachment of a leadwire.

In the finished socket member the, two wing pieces l5 form contact elements which are helically disposed in relation to a centre line through the access opening to the socket. As a result, for any given depth of socket, it is possible to provide greater resilience than could be obtained with contact elements extending parallel with the socket axis. In consequence the amount of metal in the socket may be cut down to a minimum, thus reducing capacity effects.

At the narrow end of the tube (see Figure 4) the wing pieces [5 encompass'more than a semicircle (i. e., more than half of the circumference of the contact pin when in position in the tube) with the advantage that no reliance need be placed on the tag element to provide any part of the necessary pressure on the valve or other cooperating contact pin. In consequence, any deformation of the tag element which may be occasioned by the attachment of a lead wire or by the spreading out of the element will not impair the efficiency of the socket.

In the construction shown in Figure 4 the wing pieces, at the narrow end of the tube are struck from a centre coincident with the main axis of the socket tube. They may, however, be, and it is in some cases preferred that they are, struck from separated centres which, when there is no plug pin within the member, lie in a plane offset from the main axis of the socket towards the tag element.

When the socket member is to be used in conjunction with a contact pin which (as is common in thermionic valves) is formed with a bulge intermediate in its length, the depth of the socket is preferably such that when the pin has been fully inserted the maximum diameter of the bulge will have passed the narrow end of the socket.

It is of considerable advantage to be able to manufacture sockets of the kind in question from rolled brass strip instead of having to turn or otherwise form them out of solid cylindrical material. By the adoption of rolled strip, not only is the time of manufacture reduced considerably, but the finished article is more satisfactory from a users point of view because rolled strip can be obtained and worked with a hard springy characteristic, whereas rods or bars from which turnings are made must be of a much softer material. It is possible, therefore, by using strip to provide a contact with much better contact pressure and generally much lighter in construction.

A further advantage arising from the use of strip material is that the contact socket can easily be provided "with a relatively large terminal tag to which external connections can readily be soldered. The size of the tag not only facilitates the soldering operation, but its remoteness from the contact surfaces of the socket ensures that with normal care none of the products of soldering are likely to contaminate such surfaces.

The advantage of the open end construction over a construction having one end closed is that adequate circulation of electrolyte may take place through the socket whilst the socket is being electro-plated, thus ensurin that the contact surfaces are uniformly coated with the desired plating.

Another point which again tends to emphasize the advantage of using rolled sheet in the construction of the socket is that instead of having to spin the end of the socket to secure it to the insulating plate the end may be riveted over, the operation being much speedier than turning.

I claim:

1. An electrical socket member of tubular form divided over a substantial portion of its length into three tongues by three parallel-sided openended slots formed in the tubular wall and extending as to one slot lengthwise of the tube and as to the other two slots obliquely to the length of the tube, the tongue located between the two slots being of extended length and constituting an attachment lug for a lead wire and the other two tongues together encompassing more than a semicircle of radius which is, at the free ends of the tongues, smaller than the radius of the extended tongue at the same position in the length of the socket and together providing the whole of the contact pressure on the co-operating plug in.

2. An electrical socket member of tubular form divided over a substantial portion of its length into three tongues by three parallel-sided openended slots formed in the tubular wall and extending as to one slot lengthwise of the tube and as to the other two slots obliquely to the length of the tube, the tongue located between the two slots being of extended length and constituting an attachment lug for a lead wire and the other two tongues together encompassing more than a semicircle of radius which is, at the free ends of the two tongues, smaller than the radius of the extended tongue at the same position in the length of the socket and which is struck from a center ofiset from the main axis of the contact towards the extended tongue.

3. An electrical socket member of tubular form divided over a substantial portion of its length into three tongues by three parallel-sided openended slots formed in the tubular wall and extending as to one slot lengthwise of the tube and as to the other two slots obliquely to the length of the tube, the tongue located between the two slots bein of extended length and constituting an attachment lug for a lead wire and the other two tongues together encompassing more than half the circumference of the socket and at one end of the contact at least bein struck from separated centers which centers, when there is no plug-pin in position in the member, are offset from the main axis of the socket towards the extended tongue.

STANLEY THOMAS DEAKIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,768,669 Davis July 1, 1930 2,004,076 Knutson June 4, 1935 2,068,230 Franklin Jan. 19, 1937 2,128,132 Frederick Aug. 23, 1938 

